Generally, radio frequency identification (RFID) systems include an RFID transponder (also referred to as an RFID tag or tag), and an RFID reader or interrogator, which may be communicably coupled to a host computer. The reader, which may be configured either as a handheld or a fixed-mount device, includes a transceiver that transmits an electromagnetic interrogation or activation signal for detection by transponders, and that receives signals transmitted by RFID tags (e.g., usually in response to the activation signal). Each RFID transponder stores unique information (e.g., an identification code) and/or other data that may be wirelessly read by the reader or interrogator when the transponder is located close enough to the reader to detect the reader's activation signal. More specifically, the reader receives and decodes unique information and/or data encoded in the tag, and may pass this information to the host computer for processing. In various applications, such as premises or equipment access control, RFID tags are integrated with or otherwise incorporate a biometric sensor to ensure that the RFID tag is in possession of the authorized user to whom the tag was issued.
Depending on the application and corresponding tag design (e.g., type of memory used in the tag), data stored in the tag may be read-only, write once read many (WORM), or read/write. Read-only tags typically are programmed by a manufacturer or distributor with a unique identifier, which in various applications identifies an item to which the tag is attached. WORM and read/write tags provide for field or user programmability of the unique information (e.g., identification) and/or other data stored in the tag. For example, WORM tags are typically used to allow for the unique information to be programmed into the tag by an OEM customer, an end user, or a tag distributor, rather than by the tag manufacturer. Read/write tags further allow the user to change data (e.g., write data to the tag more than one time and/or rewrite or modify data stored in the tag), which may be useful in applications such as those where the tag is used for monitoring processes or transactions experienced by the associated item or device (e.g., work-in-process or maintenance tracking). Accordingly, information or data stored in the tag is programmed at manufacturing and/or in the field by an external programmer (e.g., reader/interrogator).